I just received a great Adcom 535 Power Amp as a gift. A friend bought it on ebay and had it sent to my door. Very cool gift and great friend.

Anyways, I'm wondering if this is stock. It looks like it's had a couple of caps added. I have no idea if they were original or a Mod of some sort. Curious on thoughts. This is one of my first Hi Fi amplifiers.
thanks!!
Nick

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NOTE: the red Poly cap soldered in the same hole as the resistor at the edge of the board.

Originally posted by Nelson Pass Don't look at me, I have no idea. I suggest that you contact Adcom for
a copy of the service manual.

LOL! Did you design this one?

btw... if this is not supposed to be in this forum, I apologize. I'm totally cool with it being moved if it needs to be. I noticed other Adcom information posted here so figured this is where the fans of the 80's Adcom stuff would be.

Designing for Adcom consisted of creating an original piece with
documentation. From that they made production pieces with their
own artwork and such. They did have a good technical staff, so the
products tended to mutate over time, and some new products were
created by simply scaling down a larger piece.

If you look at schematic for the 555 you'll see two electrolytics, a large one in the F/B circuit and a smaller one in the bias circuit. The large one is bypassed by a .1uf film capacitor. Now look at the picture of the 535 board, if you check out the components around the large electrolytic all of the values are the same as the 555 and appears the film capacitor was added as the bypass after the board was made. Also there are many empty part locations, less outputs and associated components, probably the same board. Anyway that's WHAT it is, how,who, when, and why are still the questions. I wonder if the original 555 had the bypass?